1. Field of the Invention
The present invention relates to an image pickup apparatus, such as a video camera.
2. Description of the Related Art
Conventionally, there is known an image pickup apparatus having a live view mode configured to continuously output image data from an image pickup element and to display it on a display unit. It is also known to detect an object and its motion from an output of the image pickup element and to provide autofocusing (AF). Moreover, Japanese Patent Laid-Open No. (“JP”) 05-297433 proposes an image pickup apparatus configured to calculate an aperture value that provides a set depth of field, and to adjust exposure through a shutter speed while the stop is set to the calculated aperture value.
JP 05-297433 maintains constant the depth of field and thus the blur degree of an object to be followed does not change. However, an exposure time period of the image pickup element varies, and the object may not be followed because blurs of the object, etc. can change.